Abstract
Seawater desalination is considered a technique with high water supply potential and has become an emerging alternative for freshwater supply in China. The increase of the capacity also increases energy consumption and greenhouse gases (GHG) emissions, which has not been well investigated in studies. This study has analyzed the current development of seawater desalination in China, including the capacity, distribution, processes, as well as the desalted water use. Energy consumption and GHG emissions of overall desalination in China, as well as for the provinces, are calculated covering the period of 2006–2016. The unit product cost of seawater desalination plants specifying processes is also estimated. The results showed that 1) The installed capacity maintained increased from 2006 to 2016, and reverse osmosis is the major process used for seawater desalination in China. 2) The energy consumption increased from 81 MWh/y to 1,561 MWh/y during the 11 years. The overall GHG emission increase from 85 Mt CO2eq/y to 1,628 Mt CO2eq/y. Tianjin had the largest GHG emissions, following are Hebei and Shandong, with emissions of 4.1 Mt CO2eq/y, 2.2 Mt CO2eq/y. and 1.0 Mt CO2eq/y. 3) The unit product cost of seawater desalination is higher than other water supply alternatives, and it differentiates the desalination processes. The average unit product cost of the reverse osmosis process is 0.96 USD and 2.5 USD for the multiple-effect distillation process. The potential for future works should specify different energy forms, e.g. heat and power. Alternatives of process integration should be investigated—e.g. efficiency of using the energy, heat integration, and renewables in water desalination, as well as the utilization of total site heat integration.
Highlights
Increasing water scarcity has become a global issue
The energy consumption, GHG emission, and the unit product cost of the seawater desalination plants in China are assessed for the year of 2006–2016
ECa = ∑ SECi × Ci × 365 × Pa where ECa is the annual energy consumption of the plant, kWh/y; SECi is the specific energy consumption of seawater desalination plants with process i, kWh/m3 ; the energy consumption of all desalination processes involved in this study (RO, multiple-effect distillation (MED), multi-stage flash (MSF), and ED) are converted to the form of electricity, kWh/m3 ; Ci is the capacity of the desalination plants with process i, m3 /d
Summary
Increasing water scarcity has become a global issue. Freshwater supply is limited and has been remarkably affected by the degradation of water quality in natural water bodies, while the demand for freshwater has continued to increase. Besides water consumption minimization by improving water use efficiency, conventional water treatment and desalination are employed to reclaim the polluted water and freshwater to increase the supply. In water-scarce regions, where the water source is mainly from precipitation, the water supply has been unreliable due to the influence of global climate change [1]. Water desalination has been widely applied in the world.
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